Answer
Work through this checklist before escalating: first check the customer record itself is fully set up for the company the order is being created in, and for every Address ID used by the order, confirm Address Info is populated on both the General Address Info tab and the Order Address Info tab (it's very often specifically the Order Address Info tab that's missing for a given address). Next, validate by manually creating a Customer Order for that same customer and confirm no errors occur with the current setup. If manual creation works cleanly, then check that the incoming EDI message's connection is actually mapping correctly — review the Incoming Customer Order messages for that customer for further clues. Only after all of this checks out clean (and especially if the customer has worked before with no recent changes) does it make sense to escalate to a support case, since the root cause is very often a specific incomplete address record rather than something requiring code-level investigation.